Submersible pump

ABSTRACT

A submersible pump includes: a single phase motor having a drive shaft extending in the vertical direction; a pump assembly which is driven by the single phase motor; a motor casing in which the single phase motor is contained; an external casing in which the motor casing is inserted to form an annular channel between the external casing and the outer circumferential surface of the motor casing; and a capacitor. The capacitor is arranged on the side of the single phase motor in the motor casing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a submersible pump.

2. Description of Related Art

A submersible pump in which water flows along the entire circumference thereof has been known as a temporary submersible pump used for drainage in a construction site (for example, see Japanese Patent No. 3239179).

The submersible pump of this kind includes a motor, a motor casing and a substantially cylindrical external casing. The motor has a drive shaft extending in the vertical direction and the motor casing contains the motor therein. The external casing forms an annular channel in association with the outer circumferential surface of the motor casing between them and a discharge port is formed in the external casing to communicate with the annular channel. The submersible pump is configured such that fluid is drained out through the annular channel and the discharge port as a pump assembly is driven by the motor.

When the motor of the submersible pump is a single phase motor, a capacitor is required to operate it. In the conventional submersible pump according to the above publication, the capacitor is arranged above the motor.

Submersible pumps for temporary use as described above are generally equipped with a handle for easy portability. Therefore, they are required to be small in size. However, the above-described submersible pump, which includes the capacitor arranged above the motor, becomes large in height.

SUMMARY OF THE INVENTION

The present invention has been achieved in this respect. That is, an object of the invention is to reduce the size of the submersible pump to a further extent.

According to an aspect of the present invention, a submersible pump includes: a single phase motor having a drive shaft extending in the vertical direction; a pump assembly which is driven by the single phase motor; a motor casing in which the single phase motor is contained; an external casing in which the motor casing is inserted to form an annular channel between the external casing and the outer circumferential surface of the motor casing; and a capacitor which is arranged on the side of the single phase motor in the motor casing.

With this configuration, the capacitor, which has been arranged above the single phase motor in the conventional pump, is provided on the side of the single phase motor. This eliminates the need of ensuring space for installing the capacitor above the single phase motor, thereby reducing the height of the submersible pump.

Further, as an annular channel is formed around the single phase motor (motor casing), the capacitor arranged on the side of the single phase motor is located within the annular channel. Therefore, there is no need of increasing the size of the external casing. That is to say, the outside diameter of the submersible pump is not increased even if the capacitor is arranged on the side of the single phase motor. Thus, the submersible pump is reduced in size.

The single phase motor may be arranged such that the drive shaft thereof is eccentric to the center of the external casing in a certain direction of eccentricity and the capacitor may be arranged on the side of the single phase motor opposite the certain direction of eccentricity.

If the single phase motor is arranged eccentrically with respect to the external casing, the annular channel, which is formed between the motor casing and the external casing, becomes relatively large in a portion thereof opposite the direction of eccentricity of the single phase motor.

As the relatively large portion of the annular channel is reserved for the capacitor, it becomes possible to arrange a capacitor with increased capacitance and size therein.

The submersible pump may further include a motor cover which closes an upper opening end of the motor casing. Further, the motor cover may be attached with a bearing for supporting the drive shaft of the single phase motor.

As described above, since the capacitor is arranged on the side of the single phase motor, there is no need of ensuring space for installing the capacitor above the single phase motor. This makes it possible to attach the bearing for supporting the drive shaft directly to the motor cover which closes the upper opening end of the motor casing. Therefore, a bracket for the bearing is no longer necessary, thereby reducing the number of components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a submersible pump according to an embodiment of the present invention taken along the line I-I of FIG. 3.

FIG. 2 is a sectional view taken along the line II-II of FIG. 3.

FIG. 3 is a plan view of the submersible pump.

FIG. 4 is a sectional view taken along the line IV-IV of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 are sectional views of a submersible pump 1 according to an embodiment of the present invention. The sectional views of FIGS. 1 and 2 are taken along the lines I-I and II-II of FIG. 3, respectively.

The submersible pump 1 is a temporary pump used for drainage, for example. The submersible pump 1 includes a pump assembly 2 having an impeller 21 and a motor assembly 3 having a motor 4 for driving the impeller 21. The pump assembly 2 is provided below an oil casing 6 and the motor assembly 3 is provided above it. That is, the pump assembly 2 and the motor assembly 3 are aligned in the vertical direction.

In addition to the motor 4, which is formed of a stator 41 and a rotor 42, the motor assembly 3 further includes a stator casing (motor casing) 31 and a motor cover 32. The stator casing 31 covers the stator 41 of the motor 4 and the motor cover 32 is attached to the upper end of the stator casing 31.

The motor 4 is a single phase motor and includes a drive shaft 43 arranged substantially in the middle thereof to extend in the vertical direction. The lower end of the drive shaft 43 is connected to the impeller 21 such that the rotation of the motor 4 is transferred to the impeller 21.

The stator casing 31 includes a casing body 31 a in the form of a cylinder with the lower end closed and the upper end opened. A through hole is formed substantially in the middle of the bottom of the casing body 31 a to let the drive shaft 43 extend therethrough. Further, a bearing 33 is attached to the bottom of the casing body 31 a to support the drive shaft 43 at a substantially middle part thereof in a rotatable manner.

The stator casing 31 further includes a container part 31 b for containing a capacitor 34 used to operate the motor 4. As shown in FIG. 4, the container part 31 b is configured to protrude outward from the outer circumferential surface of the casing body 31 a in the radial direction.

As shown in FIG. 4, the stator casing 31 is configured such that the center of the casing body 31 a, i.e., the center X2 of the drive shaft 43 of the motor 4, is eccentric to the center X1 of an external casing 5 to be explained later. The container part 31 b is configured to protrude in a direction opposite the direction of eccentricity of the casing body 31 a. That is, in FIG. 4, the container part 31 b is arranged on the left side of the casing body 31 a which is off-centered from the center X1 to the right.

The motor cover 32 is substantially in the form of inverted U when viewed in section and attached to the upper end of the stator casing 31. The motor cover 32 serves to close the upper opening end of the stator casing 31 (casing body 31 a and container part 31 b). The motor cover 32 is provided with an integral bracket 32 a formed on the inner surface of the top wall thereof. Further, a bearing 35 is attached to the bracket 32 a to support the upper end of the drive shaft 43 in a rotatable manner.

In part of the top wall of the motor cover 32 near the periphery thereof, a boss 32 b is formed to protrude upward and penetrate the external casing 5 to be explained later. A cable boot 71 is attached to the boss 32 b in a watertight manner, in which a feeder cable is inserted to feed the motor 4 with power.

Though not shown, various electrical components for driving the motor 4 are also contained in the motor cover 32.

The oil casing 6, which is substantially cylindrical, includes a partition wall 61 formed in the middle thereof in the vertical direction to divide the pump assembly 2 and the motor assembly 3. On the top surface of the partition wall 61, an integral annular wall 62 is formed to protrude upward therefrom, while on the bottom surface of the partition wall 61, an integral mount 63 is formed to protrude downward therefrom. Further, a through hole is formed in part of the partition wall 61 corresponding to the center of space enclosed with the annular wall 62, in which the drive shaft 43 of the motor 4 is inserted.

The oil casing 6 is configured such that the upper end of the annular wall 62 is fixed to the bottom surface of the casing body 31 a of the stator casing 31. As a result, enclosed space is provided by the partition wall 61, the annular wall 62 and the bottom surface of the casing body 31 a. A mechanical seal 64 is arranged in the enclosed space, while an oil seal 65 is attached onto the bottom surface of the partition wall 61.

In part of the oil casing 6 outside the annular wall 62 in the radial direction, a plurality of through holes 66 are formed intermittently along the periphery of the oil casing 6 (only a single through hole is depicted in FIGS. 1 and 2). With these through holes 66, space below the oil casing 6 (where the pump assembly 2 is provided) is communicated with space inside the external casing 5.

The external casing 5 is in the form of a cylinder with the upper end closed, i.e., substantially inverted U-shaped when viewed in section. The lower end thereof is attached to the upper end of the oil casing 6 to form a motor containing part in which the motor 4 is contained. Thus, an annular channel 51 is formed between the external casing 5 and the stator casing 31 to surround the motor 4.

A discharge port 52 is formed in part of the top wall of the external casing 5 near the periphery thereof to communicate with the annular channel 51. A hose coupling 53 is attached to the discharge port 52. Further, a handle 54 for carrying the submersible pump 1 is attached to the top of the external casing 5.

In addition to the impeller 21 attached to the lower end of the drive shaft 43 of the motor 4 as described above, The pump assembly 2 includes a pump casing 22.

The pump casing 22 is substantially in the form of a cylinder with the lower end closed, i.e., substantially U-shaped when viewed in section. The pump casing 22 is fitted into the mount 63 of the oil casing 6 to cover the impeller 21 from below.

A suction port 22 a is formed in part of the bottom of the pump casing 22 corresponding to the center of the impeller 21. Accordingly, the suction port 22 a becomes eccentric to the center X1 of the external casing 5.

Reference numeral 23 indicates a rear liner arranged on the rear side of the impeller 21 and sandwiched between the pump casing 22 and the oil casing 6.

Further, a strainer 7 is arranged below the oil casing 6 to cover the pump casing 22. The strainer 7 is substantially in the form of a cylinder with the lower end closed, i.e., substantially U-shaped when viewed in section, and provided with a plurality of suction holes 72 on the outer circumferential surface thereof. As the upper end of the strainer 7 is attached to the lower end of the oil casing 6, a pump containing part is formed by the strainer 7 and the oil casing 6 in which the pump assembly 2 is contained.

With the thus-configured submersible pump 1, for example, water pooled in a hole bored in a construction site is drained. First, an end of an exhaust hose (not shown) is connected to the hose coupling 53. Then, the submersible pump 1 is placed in the hole to stay underwater and the motor 4 is actuated.

As a result, the impeller 21 rotates to generate centrifugal force, which causes water around the impeller 21 to move out in the lateral direction. Then, pressure drops in a region below the center of the impeller 21. Due to the pressure drop, water outside the strainer 7 is sucked into the pump casing 22 through the suction holes 72 and the suction port 22 a. The sucked water is also extruded in the lateral direction by the centrifugal force and guided to the annular channel 51 in the external casing 5 via the through holes 66 formed in the oil casing 6. When a predetermined amount or more of water is accumulated in the annular channel 51, it is ejected out through the discharge port 52 and the exhaust hose. Thus, the water pooled in the hole is drained.

In the submersible pump 1, a capacitor 34 for actuating the single phase motor 4 is arranged on the side of the motor 4. This configuration eliminates the need of ensuring space for installing the capacitor above the motor 4. Therefore, the height of the submersible pump 1 is reduced.

The motor 4 is arranged eccentrically with respect to the external casing 5. Therefore, the annular channel 51 formed along the entire circumference of the motor 4, which is defined by the stator casing 31 and the external casing 5, becomes larger in a portion thereof opposite the direction of eccentricity of the motor 4 than the other portion. The capacitor 34 is arranged in the larger portion of the annular channel 51. Therefore, even if the capacitor 34 is arranged on the side of the motor 4, the outside diameter of the submersible pump 1 is not increased so much. As a result, the submersible pump 1 is drastically reduced in size as compared with the conventional one. Thus, the submersible pump 1 is improved in portability.

Since the capacitor 34 is arranged in the larger portion of the annular channel 51, the capacitor 34 may have larger capacitance, which is accompanied by a larger outside diameter. By so doing, the motor 4 is provided with large starting torque.

Further, as the capacitor 34 is not arranged above the motor 4, it becomes possible to form the bracket 32 a, to which the bearing 35 for supporting the drive shaft 43 is attached, integrally with the motor cover 32. Therefore, the number of components is reduced as compared with the conventional submersible pump which requires a separate bearing bracket.

In the above-described embodiment, the motor 4 is arranged eccentrically with respect to the external casing 5. However, it may be possible to arrange the motor 4 concentrically with the external casing 5. Even in such a case, the annular channel 51 is formed around the motor 4. Therefore, the capacitor is arranged within the channel. Thus, the submersible pump with reduced height is achieved without increasing its outside diameter.

It should be noted that the present invention is not limited to the above embodiment and various modifications are possible within the spirit and essential features of the present invention. The above embodiment shall be interpreted as illustrative and not in a limiting sense. The scope of the present invention is specified only by the following claims and the description of the specification is not limitative at all. Further, it is also to be understood that all the changes and modifications made within the scope of the claims fall within the scope of the present invention. 

1. A submersible pump comprising: a single phase motor having a drive shaft extending in the vertical direction; a pump assembly which is driven by the single phase motor; a motor casing in which the single phase motor is contained; an external casing in which the motor casing is inserted to form an annular channel between the external casing and the outer circumferential surface of the motor casing; and a capacitor which is arranged on the side of the single phase motor in the motor casing.
 2. The submersible pump of claim 1, wherein the single phase motor is arranged such that the drive shaft thereof is eccentric to the center of the external casing in a certain direction of eccentricity and the capacitor is arranged on the side of the single phase motor opposite the certain direction of eccentricity.
 3. The submersible pump of claim 1 further comprising a motor cover which closes an upper opening end of the motor casing, wherein the motor cover is attached with a bearing for supporting the drive shaft of the single phase motor. 